Science: Insect Masquerade

Naturalists have noticed for at least a century that insects have a way
of mimicking each other. Butterflies of two species not closely related
often show similar patterns of bright colors. Generations of
entomologists have suspected that nature thus protects a butterfly that
birds consider delicious by enabling it to resemble one that is
distasteful to birdsbut this theory has been widely debated and
rarely tested experimentally. In Natural History, Biologists Lincoln P.
and Jane Van Zandt Brower of Amherst College settle at least part of
the argument about the survival value of nature's insect masquerade.